Seismic Damage Characteristics of Cripple Walls

Abstract

Significant losses were reported for wood-framed construction during past earthquakes in California due to damage or collapse of cripple walls in single-family residential buildings. A common cripple wall failure involves the upper stories shifting laterally over the “soft” unbraced cripple wall, causing the building to drop vertically, which in turn causes fracture of sewer, water, and gas lines, and often leads to irreparable loss of the building. This paper presents results from a series of in-plane level and stepped cripple wall tests, which were conducted as a part of the CUREE-Caltech Woodframe Project. Specimens with details representative of current retrofit and new construction were tested using displacement histories recommended for near-fault and ordinary ground motions. Code requirements and previous research on cripple walls are first reviewed, followed by a presentation of the damage characteristics of cripple walls. The effects of loading histories on the response of cripple walls are also described.